1. Field of the Invention
This invention relates to the developing and processing of photographic film and print paper, and especially, but not exclusively, to the development and processing of color film and paper.
2. Brief Description of Prior Art
Safelights for darkroom use in connection with the development and processing of black-and-white film and print paper are well-known to the art. They perform their intended function (when properly used) without adverse effect, i.e., fogging, upon the film or print paper being developed. However, no satisfactory safelight for color film and print paper developing has heretofore been perfected. In all cases known to applicant, conventional safelights for color processing transmit so little light that it is difficult to inspect the film or print paper being processed. Not only is the illumination level extremely low, but the exposure time for each inspection period must be kept relatively short to prevent fogging of the light-sensitive material.
As an example, the processing of color print paper requires the use of an unusually dense safelight filter such as that marketed by the Eastman Kodak Company under the trademark KODAK NO. 10. This is a very dark amber filter which may be used with color-negative paper, color slide and print material and panchromatic paper. The filter is normally used with a fifteen-watt incandescent lamp and is positioned no closer than four feet from the light-sensitive material which is to be inspected. The light available under these conditions is extremely limited, and inspection of the light-sensitive material and any photographic image thereon is difficult. Increasing the wattage of the light source or reducing the distance between the light source and the light-sensitive material being processed is likely to result in fogging of the light-sensitive material.
The closest prior patent art known to applicant consists of the following U.S. Pat. Nos.:
Ryan No. 2,263,684 McClees No. 2,979,601 Wood No. 1,649,638 Thomas No. 2,431,091 Metcalfe No. 3,342,119 Strong No. 2,603,133 Potter No. 2,356,694 Engelage No. 3,107,578 Yutzy No. 3,497,350
The McClees U.S. Pat. No. 2,979,601 teaches the making of a light filter by exposing photographic film to a controlled light source and then developing same. But it does not appear that this patent teaches the use of a color negative film exposed to white light and developed with color developer and used in combination with color filters as a safelight filter. The McClees filter is not intended to function as a darkroom safelight filter and it is incapable of performing that function.
The remaining prior art patents above cited show various kinds of light filters, including filters for darkroom safelights, e.g., Ryan U.S. Pat. No. 2,263,684 which teaches the use of polarized filters for that purpose. But there is no teaching in Ryan, or in any of the other prior art references, of the use of color negative film (exposed to white light and developed with color developer) as a darkroom safelight filter in combination with color filters as herein disclosed.